PR c++/88335 - Implement P1073R3: Immediate functions

	PR c++/88335 - Implement P1073R3: Immediate functions
c-family/
	* c-common.h (enum rid): Add RID_CONSTEVAL.
	* c-common.c (c_common_reswords): Add consteval.
cp/
	* cp-tree.h (struct lang_decl_fn): Add immediate_fn_p bit.
	(DECL_IMMEDIATE_FUNCTION_P, SET_DECL_IMMEDIATE_FUNCTION_P): Define.
	(enum cp_decl_spec): Add ds_consteval.
	(fold_non_dependent_expr): Add another tree argument defaulted to
	NULL_TREE.
	* name-lookup.h (struct cp_binding_level): Add immediate_fn_ctx_p
	member.
	* parser.c (cp_keyword_starts_decl_specifier_p): Adjust comments
	for C++11 and C++20 specifiers.  Handle RID_CONSTEVAL.
	(CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR): Adjust comment.
	(CP_PARSER_FLAGS_CONSTEVAL): New.
	(cp_parser_skip_balanced_tokens): New forward declaration.
	(cp_parser_lambda_declarator_opt): Handle ds_consteval.  Set
	current_binding_level->immediate_fn_ctx_p before parsing parameter
	list if decl-specifier-seq contains consteval specifier.
	(cp_parser_decl_specifier_seq): Handle RID_CONSTEVAL.
	(cp_parser_explicit_instantiation): Diagnose explicit instantiation
	with consteval specifier.
	(cp_parser_init_declarator): For consteval or into flags
	CP_PARSER_FLAGS_CONSTEVAL.
	(cp_parser_direct_declarator): If CP_PARSER_FLAGS_CONSTEVAL, set
	current_binding_level->immediate_fn_ctx_p in the sk_function_parms
	scope.
	(set_and_check_decl_spec_loc): Add consteval entry, formatting fix.
	* call.c (build_addr_func): For direct calls to immediate functions
	use build_address rather than decay_conversion.
	(build_over_call): Evaluate immediate function invocations.
	* error.c (dump_function_decl): Handle DECL_IMMEDIATE_FUNCTION_P.
	* semantics.c (expand_or_defer_fn_1): Use tentative linkage and don't
	call mark_needed for immediate functions.
	* typeck.c (cxx_sizeof_or_alignof_expr): Likewise.  Formatting fix.
	(cp_build_addr_expr_1): Reject taking address of immediate function
	outside of immediate function.
	* decl.c (validate_constexpr_redeclaration): Diagnose consteval
	vs. non-consteval or vice versa redeclaration.  Use
	SET_DECL_IMMEDIATE_FUNCTION_P if new_decl is immediate function.
	(check_tag_decl): Use %qs with keyword string to simplify translation.
	Handle ds_consteval.
	(start_decl): Adjust diagnostics for static or thread_local variables
	in immediate functions.
	(grokfndecl): Call sorry_at on virtual consteval.  Use %qs with keyword
	to string to simplify translation.  Diagnose consteval main.  Use
	SET_DECL_IMMEDIATE_FUNCTION_P for consteval.
	(grokdeclarator): Handle consteval.  Use %qs with keyword strings to
	simplify translation.  Use separate ifs instead of chained else if
	for invalid specifiers.  For constinit clear constinit_p rather than
	constexpr_p.
	* constexpr.c (find_immediate_fndecl): New function.
	(cxx_eval_outermost_constant_expr): Allow consteval calls returning
	void.  Diagnose returning address of immediate function from consteval
	evaluation.
	(fold_non_dependent_expr_template): Add OBJECT argument, pass it
	through to cxx_eval_outermost_constant_expr.
	(fold_non_dependent_expr): Add OBJECT argument, pass it through to
	fold_non_dependent_expr_template.
	(fold_non_dependent_init): Adjust fold_non_dependent_expr_template
	caller.
	* method.c (defaulted_late_check): Adjust diagnostics for consteval.
	* lambda.c (maybe_add_lambda_conv_op): Copy over
	DECL_DECLARED_CONSTEXPR_P and DECL_IMMEDIATE_FUNCTION_P bits from
	callop to both artificial functions.
	* init.c (build_value_init): Don't do further processing if
	build_special_member_call returned a TREE_CONSTANT.  Formatting fix.
testsuite/
	* g++.dg/cpp2a/consteval1.C: New test.
	* g++.dg/cpp2a/consteval2.C: New test.
	* g++.dg/cpp2a/consteval3.C: New test.
	* g++.dg/cpp2a/consteval4.C: New test.
	* g++.dg/cpp2a/consteval5.C: New test.
	* g++.dg/cpp2a/consteval6.C: New test.
	* g++.dg/cpp2a/consteval7.C: New test.
	* g++.dg/cpp2a/consteval8.C: New test.
	* g++.dg/cpp2a/consteval9.C: New test.
	* g++.dg/cpp2a/consteval10.C: New test.
	* g++.dg/cpp2a/consteval11.C: New test.
	* g++.dg/cpp2a/consteval12.C: New test.
	* g++.dg/cpp2a/consteval13.C: New test.
	* g++.dg/cpp2a/consteval14.C: New test.
	* g++.dg/ext/consteval1.C: New test.

From-SVN: r277733

1 files changed, 53 insertions, 6 deletions

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index f1664e6..516c14b 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -998,11 +998,13 @@ cp_keyword_starts_decl_specifier_p (enum rid keyword)
       /* GNU extensions.  */
     case RID_ATTRIBUTE:
     case RID_TYPEOF:
-      /* C++0x extensions.  */
+      /* C++11 extensions.  */
     case RID_DECLTYPE:
     case RID_UNDERLYING_TYPE:
     case RID_CONSTEXPR:
+      /* C++20 extensions.  */
     case RID_CONSTINIT:
+    case RID_CONSTEVAL:
       return true;
 
     default:
@@ -1807,12 +1809,15 @@ enum
   /* When parsing a decl-specifier-seq, only allow type-specifier or
      constexpr.  */
   CP_PARSER_FLAGS_ONLY_TYPE_OR_CONSTEXPR = 0x8,
-  /* When parsing a decl-specifier-seq, only allow mutable or constexpr.  */
+  /* When parsing a decl-specifier-seq, only allow mutable, constexpr or
+     for C++2A consteval.  */
   CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR = 0x10,
   /* When parsing a decl-specifier-seq, allow missing typename.  */
   CP_PARSER_FLAGS_TYPENAME_OPTIONAL = 0x20,
   /* When parsing of the noexcept-specifier should be delayed.  */
-  CP_PARSER_FLAGS_DELAY_NOEXCEPT = 0x40
+  CP_PARSER_FLAGS_DELAY_NOEXCEPT = 0x40,
+  /* When parsing a consteval declarator.  */
+  CP_PARSER_FLAGS_CONSTEVAL = 0x80
 };
 
 /* This type is used for parameters and variables which hold
@@ -2671,6 +2676,7 @@ static bool cp_parser_init_statement_p
   (cp_parser *);
 static bool cp_parser_skip_to_closing_square_bracket
   (cp_parser *);
+static size_t cp_parser_skip_balanced_tokens (cp_parser *, size_t);
 
 // -------------------------------------------------------------------------- //
 // Unevaluated Operand Guard
@@ -10903,11 +10909,31 @@ cp_parser_lambda_declarator_opt (cp_parser* parser, tree lambda_expr)
      opening parenthesis if present.  */
   if (cp_lexer_next_token_is (parser->lexer, CPP_OPEN_PAREN))
     {
+      bool is_consteval = false;
+      /* For C++20, before parsing the parameter list check if there is
+	 a consteval specifier in the corresponding decl-specifier-seq.  */
+      if (cxx_dialect >= cxx2a)
+	{
+	  for (size_t n = cp_parser_skip_balanced_tokens (parser, 1);
+	       cp_lexer_nth_token_is (parser->lexer, n, CPP_KEYWORD); n++)
+	    {
+	      if (cp_lexer_peek_nth_token (parser->lexer, n)->keyword
+		  == RID_CONSTEVAL)
+		{
+		  is_consteval = true;
+		  break;
+		}
+	    }
+	}
+
       matching_parens parens;
       parens.consume_open (parser);
 
       begin_scope (sk_function_parms, /*entity=*/NULL_TREE);
 
+      if (is_consteval)
+	current_binding_level->immediate_fn_ctx_p = true;
+
       /* Parse parameters.  */
       param_list
 	= cp_parser_parameter_declaration_clause
@@ -10992,6 +11018,9 @@ cp_parser_lambda_declarator_opt (cp_parser* parser, tree lambda_expr)
 		    "lambda only available with %<-std=c++17%> or "
 		    "%<-std=gnu++17%>");
       }
+    if (lambda_specs.locations[ds_consteval])
+      return_type_specs.locations[ds_consteval]
+	= lambda_specs.locations[ds_consteval];
 
     p = obstack_alloc (&declarator_obstack, 0);
 
@@ -14052,6 +14081,11 @@ cp_parser_decl_specifier_seq (cp_parser* parser,
 	  cp_lexer_consume_token (parser->lexer);
 	  break;
 
+	case RID_CONSTEVAL:
+	  ds = ds_consteval;
+	  cp_lexer_consume_token (parser->lexer);
+	  break;
+
         case RID_CONCEPT:
           ds = ds_concept;
           cp_lexer_consume_token (parser->lexer);
@@ -14169,7 +14203,8 @@ cp_parser_decl_specifier_seq (cp_parser* parser,
       if (found_decl_spec
 	  && (flags & CP_PARSER_FLAGS_ONLY_MUTABLE_OR_CONSTEXPR)
 	  && token->keyword != RID_MUTABLE
-	  && token->keyword != RID_CONSTEXPR)
+	  && token->keyword != RID_CONSTEXPR
+	  && token->keyword != RID_CONSTEVAL)
 	error_at (token->location, "%qD invalid in lambda",
 		  ridpointers[token->keyword]);
 
@@ -17310,6 +17345,10 @@ cp_parser_explicit_instantiation (cp_parser* parser)
 	    permerror (decl_specifiers.locations[ds_constexpr],
 		       "explicit instantiation shall not use"
 		       " %<constexpr%> specifier");
+	  if (decl_spec_seq_has_spec_p (&decl_specifiers, ds_consteval))
+	    permerror (decl_specifiers.locations[ds_consteval],
+		       "explicit instantiation shall not use"
+		       " %<consteval%> specifier");
 
 	  decl = grokdeclarator (declarator, &decl_specifiers,
 				 NORMAL, 0, &decl_specifiers.attributes);
@@ -20295,6 +20334,9 @@ cp_parser_init_declarator (cp_parser* parser,
   bool saved_default_arg_ok_p = parser->default_arg_ok_p;
   location_t tmp_init_loc = UNKNOWN_LOCATION;
 
+  if (decl_spec_seq_has_spec_p (decl_specifiers, ds_consteval))
+    flags |= CP_PARSER_FLAGS_CONSTEVAL;
+
   /* Gather the attributes that were provided with the
      decl-specifiers.  */
   prefix_attributes = decl_specifiers->attributes;
@@ -20939,6 +20981,10 @@ cp_parser_direct_declarator (cp_parser* parser,
 
 	      begin_scope (sk_function_parms, NULL_TREE);
 
+	      /* Signal we are in the immediate function context.  */
+	      if (flags & CP_PARSER_FLAGS_CONSTEVAL)
+		current_binding_level->immediate_fn_ctx_p = true;
+
 	      /* Parse the parameter-declaration-clause.  */
 	      params
 		= cp_parser_parameter_declaration_clause (parser, flags);
@@ -29960,9 +30006,10 @@ set_and_check_decl_spec_loc (cp_decl_specifier_seq *decl_specs,
 	    "friend",
 	    "typedef",
 	    "using",
-            "constexpr",
+	    "constexpr",
 	    "__complex",
-	    "constinit"
+	    "constinit",
+	    "consteval"
 	  };
 	  gcc_rich_location richloc (location);
 	  richloc.add_fixit_remove ();